Cerebral coherence between communicators marks the emergence of meaning

Significance Building on recent electrophysiological evidence showing that novel communicative behavior relies on computations that operate over temporal scales independent from transient sensorimotor behavior, here we report that those computations occur simultaneously in pairs with a shared communicative history, but not in pairs without a shared history. This pair-specific interpersonal synchronization was driven by communicative episodes in which communicators needed to mutually adjust their conceptualizations of a signal’s use. That interpersonal cerebral synchronization was absent when communicators used stereotyped signals. These findings indicate that establishing mutual understanding is implemented through simultaneous in-phase coordination of cerebral activity across communicators, consistent with the notion that pair members temporally synchronize their conceptualizations of a signal’s use.